Fines are sometimes produced during production in subterranean wells, such as oil or gas wells, or the like, which contain chalk or other calcium carbonates, or which contain sandstone which may or may not include calcium carbonate cementitious material. These fines can cause the fractures in the formation to become blocked and thus decrease the production rate of the well. It is necessary to consolidate these fines in a reliable way so that the fractures do not become blocked and well production is not hampered.
It is known to use calcium carbonate in a silicate containing solution in sealant compositions. U.S. Pat. No. 4,762,443 describes a fluid composition comprising a sodium metasilicate and a calcium carbonate which is used to make porous material impervious by injecting the composition into the material, which will then harden and set over time.
In some chalk formations such as, for example, the Valhall field in Norway, the chalk reservoir formation produces fines during production. The first completions in this field were cased-hole gravel stacks, but these were quickly blocked by the chalk fines production, as disclosed in Paper Number 36899-MS entitled “Multiple Proppant Fracturing of a Horizontal Wellbore: an integration of two technologies” 1996 published by the Society of Petroleum Engineers.
More recently wells have been completed with multiple propped hydraulic fractures. Although these have been very successful, there is still a tendency for the propped fractures to become plugged thus reducing production. The present invention has the advantage of providing a more reliable consolidation of the formation. It also further could be used to limit or prevent lost circulation in fractured carbonate formations.